A DNA database system is helping authorities prosecute and convict poachers and rhino horn traffickers in Africa.

RhODIS, as the system is called, is built on a foundational database with genetic information from nearly 4,000 individual rhinos.

By comparing the frequencies of alleles in confiscated horn and horn products with those in tissue from a poached animal, investigators can then come up with a probable match for where that horn came from.

So far, RhODIS has been instrumental in nine convictions in East and Southern Africa.

Authorities protecting rhinos in Africa now have a tool to help them catch poachers based on fine-scale differences in the DNA of different individuals.

The Rhino DNA Index System, or RhODIS for short, has already been used in nine cases to help convict people involved in the illicit rhino horn trade in East and Southern Africa.

One defendant tried for the killing of two white rhinos (Ceratotherium simum) in South Africa’s Kruger National Park was sentenced to more than 29 years in prison.

“Unlike similar work in which genetic databases provide an indication of geographic provenance, [RhODIS] provides individual matches that, similar to human DNA profiling, is used as direct evidence in criminal court cases,” Cindy Harper, a veterinarian at South Africa’s University of Pretoria, said in a statement.

Poachers and rhino horn traffickers have a significant advantage in staying a step ahead of law enforcement because it’s difficult to pinpoint the rhino horn’s exact origin.

Once the horn is cut from a rhino’s body, it moves quickly into the market stream and off to countries where rhino horn is prized for its ornamental value or as a component in traditional medicines.

Much of that demand comes from China and Vietnam. RhODIS provides an expedient way for investigators to connect confiscated rhino horn products with the place where its owner was killed.

Harper and her colleagues have banked DNA from more than 3,000 white rhinos and nearly 900 black rhinos (Diceros bicornis) and looked at how often different variants of genes, known as alleles, occur in different populations.

By comparing the frequencies of alleles in the horn with those in tissue from a poached animal, they can then come up with a probable match for where that horn came from.

Rhino poaching has risen rapidly in recent years, with some 6,100 killed illegally in South Africa in just the past nine years. More than 1,200 were killed in 2014, compared to just 13 in 2007, according to the website Stop Rhino Poaching.

Black rhinos are listed as critically endangered by the IUCN, while white rhinos carry the near threatened designation.

The authors of the study point out that the “successful prosecution, conviction and sentencing” of poachers and traffickers sets a legal precedent that could spur the use of forensic evidence in the prosecution of wildlife crime elsewhere.

But tackling the growth in the international trade of rhino horn will require international cooperation.

Various agencies in South Africa have set an example, coming together and backing the development of RhODIS, which is one reason it’s been successful, Harper said.

“Thanks to this support, we’ve seen rapid growth of the database into a representative source of rhinoceros genetic data for both forensic and management applications from its inception,” Harper said.

“The unprecedented cooperation and support for the program from these authorities has been surprising and encouraging.”